Cyclolituites applanatus ( Remelé, 1880 )

Aubrechtová, Martina & Korn, Dieter, 2022, Taxonomy and ontogeny of the Lituitida (Cephalopoda) from Orthoceratite Limestone erratics (Middle Ordovician), European Journal of Taxonomy 799 (1), pp. 1-108 : 96-98

Cyclolituites applanatus ( Remelé, 1880)

Fig. 72

Lituites applanatus Remelé, 1880: 438 .

Cyclolituites applanatus – Remelé 1886: 467; 1890: 101, pl. 1 fig. 6a–b.

Lituites applanatus – Remelé 1890: 30.

Cyclolituites applanatum – Holm 1891: 33.

Cyclolituites applanata – Neben & Krueger 1971: pl. 32 figs 19–20.

Diagnosis

Species of the genus Cyclolituites with tightly coiled conch, only last whorl detached near mature aperture; whorl profile compressed (WWI = 0.60). Shell surface with narrow annuli/raised lirae, adorally 0.5–1 mm apart, marked ventral sinus; lateral sinus weakly developed in inner whorls of the conch, shallow and asymmetric towards the aperture.

Type material

Lectotype (designated herein) GERMANY • Brandenburg, Eberswalde; Ordovician, Upper Grey Orthoceratite Limestone; Kgl. Forstakademie Eberswalde Coll.; illustrated by Remelé (1880: pl. 1 fig. 6; 1890: pl. 1 fig. 6), re-illustrated here in Fig. 72B ; MB.C.11671.2 .

Additional material

GERMANY • 1 spec.; Brandenburg, Oderberg; Ordovician, Upper Grey Orthoceratite Limestone; MB.C.30560 .

Description

Lectotype MB.C.11671.2 ( Fig. 72B ) consists of a part of the coiled conch (dm = 20 mm; one and a half tightly coiled whorls; WWI = 0.60; WER = 2.40) with an incomplete body chamber. The shell ornament consists of narrow annuli/raised lirae (up to 0.5 mm apart) separated by very fine growth lines. The ornament elements form a deep ventral sinus and a shallow lateral sinus. The slightly flattened venter of the last whorl is raised and separated from the flanks by subangular ridges. The last quarter of the last whorl belongs to the body chamber.

Specimen MB.C.30560 ( Fig. 72A ) consists of the coiled part (dm = 33 mm; one and a half tightly coiled whorls; WWI = 0.60; WER dm = 3.40) with an almost complete body chamber. The shell is ornamented by narrow annuli/raised lirae (up to 0.50–1 mm apart) and very fine growth lines in between. The ornament elements form a ventral sinus and a lateral sinus. The lateral sinus is weakly developed and shallow, the point of its maximum backward curvature is located in the ventrolateral area. As in the lectotype, the ventral side of the last whorl is slightly raised and flattened and forms a subangular ridge. The body chamber has half the length of the last whorl.

Remarks

The lectotype of C. applanatus differs from the below described specimens of C. lynceus because it has a smaller diameter of the conch (20 mm), a less compressed whorl profile (WWI = 0.60), a lower whorl expansion rate (WER 2.40) and a coarser ornament.

Specimen MB.C.30560 (also figured by Neben & Krueger 1971: pl. 32 figs 19–20) differs from the lectotype in the larger size and higher whorl expansion rate (WER = 3.40 vs 2.40 in the lectotype) and is thus similar to Cyclolituites lynnensis (late Middle or early Late Ordovician of Norway). It is possible, however, that the differences have the reason in an earlier ontogenetic growth stage of the lectotype. Since specimen MB.C.30560 has the same type of ornament and whorl profile shape (whorls are not impressed dorsally and lack a conspicuous keel ventrally) as the lectotype, it is retained in C. applanatus here.

Geographic and stratigraphic occurrence

Northern Germany (in erratics within Pleistocene gravels); Upper Grey Orthoceratite Limestone, late Lasnamägi Regional Stage, late Darriwilian, Middle Ordovician.

Figures

Fig. 72. Cyclolituites applanatus (Remelé, 1880) from the Upper Grey Orthoceratite Limestone. A. Specimen MB.C.30560 (Neben & Krueger Coll.) from Oderberg (Brandenburg); previously figured by Neben & Krueger (1971: pl. 32 figs 19–20); lateral and ventral views. B. Lectotype MB.C.11671.2 (Kgl. Forstakademie Eberswalde Coll.) from Eberswalde (Brandenburg); previously figured by Remelé (1890: pl. 1 fig. 6); lateral view. Scale bar units = 1 mm.